singular    nominative          ἡ    οἰκί    α genitive    τῆς    οἰκί    ας dative          τῇ   οἰκί    ᾳ accusative    τὴν   οἰκί    αν vocative  ὦ   οἰκί    α    plural nominative          αἱ   οἰκί    αι genitive          τῶν   οἰκι   ῶν dative    ταῖς   οἰκί    αις accusative    τὰς   οἰκί    ας vocative    ὦ   οἰκί    αι           Notes   The vocative is always the same as the nominative, in the singular as well as in the plural.   the genitive plural is always emphasized with a circumflex (sound drawn out, voice going up and then down again) on the last syllable. For all 1st declension nouns. Not adjectives! For adjectives the normal rules apply: emphasis on ultima (last syllable), circumflexed -ῶν, otherwise acute on penult (last but one), unadorned final -ων.   Accentuation All endings are short, except for genitive and dative (singular and plural) and accusative plural. Exactly like for 2nd declension nouns and adjectives. Which means that,   if the penult carries the accent and is long, that accent will be a circumflex in all forms except genitive/dative singular/plural and accusative plural. For example: ἡ σφαῖρα, τῆς σφαίρας, the ball (gave us a sphere, hemisphere = half-globe)   singular    nominative          ἡ    σφαῖρ   α genitive    τῆς    σφαίρ   ας dative  τῆ   σφαίρ   ᾳ accusative    τὴν   σφαῖρ   αν    plural nominative          αἱ   σφαῖρ   αί    genitive    τῶν   σφαιρ   ῶν dative    ταίς   σφαίρ   αις accusative    τὰς   σφαίρ   ας      if the the accent is on the antepenult (the syllable before the last but 1), e.g. ἡ μάχαιρα, a knife (In lesson 5b Philip uses a knife to deal with a troublesome wolf), the accent can only remain on the antepenult if the last syllable is short: nominative/vocative singular and plural, accusative singular. Just watch:   singular    nominative          ἡ    μάχαιρ   α genitive    τῆς    μαχαίρ   ας dative  τῇ   μαχαίρ   ᾳ accusative    τὴν   μάχαιρ   αν    plural nominative          αἱ   μάχαιρ   αι    genitive    τῶν   μαχαιρ   ῶν dative    ταίς   μαχαίρ   αις accusative    τὰς   μαχαίρ   ας